OF CONCHOLOGY. 



301 



DoRiopsis viRiDis, Pease. Plate 19, fig. 1, a, b, c. 

 Proc. Zool. Soc, London, 1861, p. 244. 

 We furnish a figure of this species in further illustration of 

 the genus. 



? Triopa gracilis, Pease. Plate 19, figs. 3, a, b, c, d. 



Body elongate, narrow, rounded above, becoming laterally 

 compressed behind the branchiae, and tapering to an acute point 

 posteriorly, rounded in front ; subpellucid, pale cream color, and 

 ornamented with small acute orange yellow papillse. 



Margin of the mantle provided with a series of tentacular pro- 

 cesses, which are the largest in front, and diminishing gradually 

 posteriorly. 



Head conspicuous and furnished with small cylindrical taper- 

 ing appendages. 



Dorsal tentacles ovate, mucronate, coarsely obliquely lamel- 

 lated, subretractile (so that the tips are only visible). Eyes 

 distinct, immediately behind the tentacles. Branchial star about 

 the middle of the body, very small, much narrower than the 

 mantle, plumules eight, rounded, arborescent, and retractile into 

 a simple common cavity. 



Vent a prominent tube. Foot very thin, pellucid, colorless, 

 widest anteriorly, gradually tapering posteriorly, where it is 

 wider and longer than the body. 



Length one inch. 



Habitat, Huaheine. 



Station, (on sea weed at low water mark. Motions lively. 



A. G.) 



Remarks. I refer the above species to genus Trio'pa with 

 some doubt, being hardly probable that it is related generically 

 to the species inhabiting Great Britian, on which the genus was 

 founded. No species, so far as I can learn, has been described 

 from the tropics. 



One has been discovered at the Cape of Good Hope and one 

 from South Australia. 



Trevelyana picta. Pease. PI. 20, fig. 1. 



Animal pellucid, smooth, very delicate, considerably com- 

 pressed, dorsal region much elevated at the middle, where it is 

 also the widest, tapering either way, more suddenly posteriorly. 

 Color pale watery white, and conspicuously marked with a few 

 remote, bright orange red circular spots, some of which are 



